Hi, would love some help here. I need to make 2 or more balls (of the same object type) to have trails.

I have attached an old capx I saved a long time ago, probably from @R0j0hound if I recall correctly. I changed a few things and tried other methods but couldn't get it to work. If you look at the capx, only one of them has trail. Hopefully someone can give me some pointers. Thanks!